Fuel injection valve assembly

ABSTRACT

A two-stage opening fuel injection valve assembly, including a valve element having an initial position providing a zero flow rate of fuel through the valve assembly, a first critical position displaced a predetermined distance from the initial position and providing a first flow rate of fuel through the valve assembly, a second critical position further displaced a predetermined distance from the first critical position and providing a second flow rate of fuel through the valve assembly, first and second movable members engageable with the valve element independently of each other, a flange member constantly engaged by the valve element and engageable with each of the first and second movable members, a first spring urging the first movable member to engage the flange member when the valve element is held in the initial position, the first spring being operative to maintain the engagement between the first movable member and the flange member when the valve element is located between the initial position and the first critical position, and a second spring urging the second movable member to engage the flange member when the valve element is moved from the initial position to one of the first and second critical positions, the second spring being operative to maintain the engagement between the second movable member and the flange member when the valve element is located between the first and second critical positions.

FIELD OF THE INVENTION

The present invention relates to a fuel injection valve for use in adiesel engine and, particularly, to a fuel injection valve of atwo-stage opening type which has two successive steps of fuel injectionfor each cycle of operation of a power cylinder of a diesel engine.

BACKGROUND OF THE INVENTION

A diesel engine using a fuel injection valve of the two-stage valveopening type is used to suppress the instability of operation typicallyrepresented by the diesel knock caused during injection of fuel. Adiesel engine of this nature is also useful for precluding the delay infiring timings and controlling the emission of nitrogen oxides.

A fuel injection valve of the two-stage valve opening type has twosuccessive fuel discharge steps for each cycle of fuel injection. Fuelis injected into the associated one of the power cylinders of the enginein quantities respectively predetermined for the two fuel dischargesteps. The quantities of the fuel to be discharged from the fuelinjection valve assembly during the two fuel discharge steps aredictated by the amounts of movement of a needle valve element 42incorporated in the fuel injection valve assembly. Specifically, thequantity of fuel to be discharged from the fuel injection valve assemblyduring the first or earlier fuel discharge step is determined by thepreliminary valve lift PL of the fuel injection valve assembly, that is,the period of time for which the needle valve element 42 is moved fromits initial axial position to a predetermined first critical axialposition of the valve element. Likewise, the quantity of fuel to bedischarged from the fuel injection valve assembly during the second orlater fuel discharge step is determined by the full valve lift FL of thefuel injection valve assembly, that is, the period of time for which theneedle valve element 42 is moved from the first critical axial positionto a predetermined second critical axial position of the valve element.A fuel injection valves of this type is disclosed in, for example,Japanese Provisional Utility Model Publication (Kokai) No. 56-129568.

The two-stage opening fuel injection valve assembly disclosed in theProvisional Utility Model Publications No. 56-129568 uses two pressuresprings which control the movements, respectively, of the needle valveelement 42 for the two fuel discharge steps of each cycle of fuelinjection. These two pressure springs are arranged in series and areseated on movable spring seat elements which are respectively associatedwith the pressure springs. One of the pressure springs contributes tothe primary valve lift for the earlier fuel discharge step and the otherto the main valve lift for the later fuel discharge step.

The prior-art fuel injection valve assembly has a drawback which resultsfrom the fact that the movable spring seat element contributing to thepreliminary valve lift of the fuel injection valve assembly is intricatein shape. Extremely high techniques are thus required for controllingthe dimensional accuracies of the spring seat element and the associatedmembers and elements during machining, assembling and adjusting of thesemembers and elements to provide a preliminary valve lift PL with asatisfactorily high degree of preciseness. It may be noted thatgenerally more exacting control is required over the preliminary valvethan over the main valve lift in a fuel injection valve assembly of thetwo-stage opening type.

Attempts have therefore been made to provide useful solutions to thisproblem of the prior-art fuel injection valve of the describedconstruction. Typical of such attempts include those which have resultedin fuel injection valves disclosed in the Japanese Provisional UtilityModel Publications (Kokai) No. 56-173757 and No. 61-184866. Theprior-art fuel injection valve shown in each of these publications ischaracterized in that the pressure springs providing the preliminary andmain valve lifts, respectively, are arranged in parallel. The parallelarrangement of the two pressure springs is useful for reducing thenumber of members and elements which affect the degree of accuracy of,particularly, the preliminary valve lift and alleviating the requirementfor high techniques in machining, assembling and adjusting the componentmembers and elements of the fuel injection valve assembly.

The improvement achieved by the prior-art two-stage opening fuelinjection valve assembly taught in these publications are however notfully satisfactory.

SUMMARY OF THE INVENTION

It is, accordingly, an important object of the present invention toprovide an improved two-stage opening fuel injection valve assemblywhich will dispense with the high techniques that have been required forthe machining, assembling and adjusting of members and elementscontributing the preliminary valve lift.

It is another important object of the present invention to provide animproved two-stage opening fuel injection valve assembly in which thepreliminary valve lift can be precisely defined without having recourseto high precision machining and can be accurately adjusted with utmostease.

It is still another important object of the present invention to providean improved two-stage opening fuel injection valve assembly in which thepreliminary valve lift is defined by members each of which issufficiently simple in shape and which can therefore be machined,assembled and adjusted with ease and manufactured at low cost.

Yet, it is still another important object of the present invention toprovide an improved two-stage opening fuel injection valve assemblywhich can utilize the needle valve element of an existing fuel injectionvalve assembly of the two-stage opening type.

In accordance with a first outstanding of the present invention, thereis provided a two-stage opening fuel injection valve assembly,comprising (a) a valve element having an initial position providing asubstantially zero flow rate of fuel through the valve assembly, a firstcritical position displaced a first predetermined distance from theinitial position in a predetermined direction and providing a first flowrate of fuel through the valve assembly, a second critical positionfurther displaced a second predetermined distance from the firstcritical position in the predetermined direction and providing a secondflow rate of fuel through the valve assembly, (b) first and secondmovable members which are engageable with the valve elementindependently of each other, (c) intermediate means constantly engagedby the valve element and engageable with each of the first and secondmovable members, (d) first biasing means urging the first movable membertoward a predetermined position to engage the intermediate means whenthe valve element is held in the initial position, the first biasingmeans being operative to maintain the engagement between the firstmovable member and the intermediate means when the valve element islocated between the initial position and the first critical position,(e) second biasing means urging the second movable member toward apredetermined position to engage the intermediate means when the valveelement is moved from the initial position to one of the first andsecond critical positions, the second biasing means being operative tomaintain the engagement between the second movable member and theintermediate means when the valve element is located between the firstand second critical positions, and (f) displacement limiting meanspreventing movement of the valve element beyond the second criticalposition in the predetermined direction.

In accordance with a second outstanding of the present invention, thereis provided a two-stage opening fuel injection valve assembly having afull valve lift and a preliminary valve lift which forms part of thefull valve lift, comprising (a) a casing structure having formed thereina fuel passageway into which is to be directed fuel under pressure, asubstantially flat fixed internal surface portion, and first and secondchambers arranged in series with each other perpendicularly to the fixedinternal surface portion, (b) first and second biasing means provided inthe first and second chambers, respectively, (c) a first movable membermovable in part within the first chambers and in part within the secondchambers, (d) a second movable member movable within the second chambersand located in the vicinity of the end of the second chambers oppositeto the first chamber, the second movable member having an end facesubstantially parallel with and confronting the fixed internal surfaceportion, the second biasing means constantly engaging the second movablemember for urging the second movable member into contact with the fixedinternal surface portion, (e) a valve element located in the vicinity ofthe second movable member and movable toward and away from the secondmovable member for controlling the flow rate of fuel through the fuelpassageway, (f) the first movable member being constantly engaged by thefirst biasing means and the valve element in the presence of fuelpressure in the fuel passageway for transmitting from the first biasingmeans to the valve element a force urging the valve element toward apredetermined initial position with respect to the second movable memberheld in contact with the fixed internal surface portion, and (g)intermediate means intervening between the first movable member and thevalve element, the intermediate means being movable with the valveelement and having an end face substantially parallel with and locatedadjacent to the end face of the second movable member, (h) the distancebetween the end face of the second movable member and the end face ofthe intermediate means engaging the valve element held in the initialposition defining the amount of the preliminary valve lift.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The drawbacks of a prior-art two-stage opening fuel injection valveassembly of the nature to which the present invention appertains and thefeatures and advantages of a two-stage opening fuel injection valveassembly according to the present invention over such a prior-arttwo-stage opening fuel injection valve assembly will be more clearlyunderstood from the following description taken in conjunction with theaccompanying drawings in which like reference numerals and charactersdesignate essentially similar or corresponding units, members, elementsand portions and in which:

FIG. 1 is a longitudinal sectional view showing an example of aconventional fuel injection valve assembly of the type to which thepresent invention generally appertains;

FIG. 2 is a sectional view showing, to an enlarged scale, the detailedconstruction of a portion of the valve assembly of FIG. 1 indicated atII in FIG. 1;

FIG. 3 is a longitudinal sectional view showing a first preferredembodiment of a fuel injection valve assembly according to the presentinvention;

FIG. 4 is a sectional view showing, to an enlarged scale, the detailedconstruction of a portion of the valve assembly of FIG. 3 indicated atIV in FIG. 3;

FIG. 5 is a longitudinal sectional view showing part of a secondpreferred embodiment of a fuel injection valve assembly according to thepresent invention;

FIG. 6 is a longitudinal sectional view showing a third preferredembodiment of a fuel injection valve assembly according to the presentinvention;

FIG. 7 is a sectional view showing, to an enlarged scale, the detailedconstruction of a portion of the valve assembly of FIG. 6 indicated atVII in FIG. 6;

FIG. 8 is a longitudinal sectional view showing part of a fourthpreferred embodiment of a fuel injection valve assembly according to thepresent invention; and

FIG. 9 is a cross sectional view taken on line IX--IX in FIG. 8 which istaken along line VIII--VIII in FIG. 9.

DETAILED DESCRIPTION OF THE PRIOR ART

Description will be hereinafter made with reference to FIGS. 1 and 2 tomore clearly show the drawbacks of a prior-art two-stage opening fuelinjection valve assembly of the type to which the present inventiongenerally appertains.

Referring first to FIG. 1, a conventional two-stage opening fuelinjection valve assembly is largely made up of a nozzle holder 10 and anozzle member 12 projecting from the nozzle holder 10 through an annularspacer element 14. The nozzle member 12 has a sleeve portion 16 and atip portion 18 projecting from the sleeve portion 16 and is formed withan axial valve chamber 20 in the sleeve portion 16 and a fuel dischargepassageway 22 in the tip portion 18 of the nozzle member 12. The fueldischarge passageway 22 in the tip portion 18 communicates with theaxial valve chamber 20 in the sleeve portion 16 and terminates in nozzleorifices 24 located at the leading end of the tip portion 18. The nozzlemember 12 is fastened to the nozzle holder 10 by means of a retainingnut member 26 with locating pins 28 secured into the nozzle holder 10and nozzle member 12 through the spacer element 14 as shown.

The nozzle holder 10 has a lug portion 29 protruding sidewise from thenozzle holder 10 and has formed therein an axial bore 30 havingthreadedly received therein an axial end portion of a connector 32formed with an axial fuel passageway 34. A fuel feed pipe leading from afuel injection pump terminates in this connector 32, though not shown inthe drawings.

The nozzle holder 10 is formed with a fuel passageway 36 leading fromthe fuel passageway 34 in the connector 32 to an aperture 38 formed inthe spacer element 14 so that the fuel directed into the fuel passageway36 in the nozzle holder 10 is passed through the aperture 38 in thespacer element 14 into a fuel passageway 40 formed in the sleeve portion16 of the nozzle member 12. The fuel passageway 40 in the sleeve portion16 of the nozzle member 12 terminates in the fuel discharge passageway22 in the nozzle member 12 so that the fuel passed to the fuelpassageway 40 in the nozzle member 12 is discharged through the nozzleorifices 24 in the nozzle member 12.

The nozzle member 12 has received therein a needle valve element 42having a guide portion 44 and a rod portion 46 axially projecting fromthe guide portion 44. The guide portion 44 is axially slidable in thevalve chamber 20 in the nozzle member 12 and the rod portion 46 extendsthrough the fuel discharge passageway 22 in the nozzle member 12 and isneedle-pointed toward the leading end of the fuel discharge passageway22. The fuel discharge passageway 22 in the nozzle member 12 is thusclosed or opened at its leading end by the pointed end of the rodportion 46 of the valve element 42 as the valve element 42 is axiallymoved in the nozzle member 12. The needle valve element 42 further has astem portion 50 projecting from the opposite end of the guide portion 44of the valve element 42. The stem portion 50 of the needle valve element42 extends through a central opening 52 formed in the spacer element 14as illustrated to an enlarged scale in FIG. 2 and projects into thenozzle holder 10.

The nozzle holder 10 is formed with an axial bore extending from one endof the nozzle holder 10 to the other and having a bore portion forming afirst spring chamber 54 terminating at the end of the nozzle holder 10close to the spacer element 14, and a bore portion forming a secondspring chamber 56 terminating at the opposite end of the nozzle holder10. The axial bore in the nozzle holder 10 further has an intermediatebore portion 58 axially intervening between the first and second springchambers 54 and 56 as shown. In the intermediate bore portion 58 of thenozzle holder 10 is closely received a sleeve member 60 formed with anaxial bore 62 extending throughout the length of the sleeve member 60.The sleeve member 60 projects at one end into the first spring chamber54 and at the other into the second spring chamber 56.

In the first and second spring chambers 54 and 56 of the nozzle holder10 are incorporated first and second pressure springs 64 and 66,respectively. The first pressure spring 64 axially extends in the firstspring chamber 54 of the nozzle holder 10 and is seated at one end on anadjustment shim 68 received on one end face of the sleeve member 60. Thepressure spring 64 is seated at the other end on a movable spring seatelement 70 located close to the spacer element 14 as shown.

As will be better seen in FIG. 2, the movable spring seat element 70 hasa flange portion 72 located close to the spacer element 14 and an axiallug portion 74 axially projecting from the flange portion 72 in adirection opposite to the spacer element 14. The stem portion 50 of theneedle valve element 42 axially projects through the opening 52 in thespacer element 14 into the first spring chamber 54 of the nozzle holder10 and engages at its leading end with the flange portion 72 of thespring seat element 70.

The first pressure spring 64 thus seated on the movable spring seatelement 70 urges the spring seat element 70 toward the inner end face ofthe spacer element 14. In the presence of fuel under pressure in the inthe fuel discharge passageway 22 in the nozzle member 12, the needlevalve element 42 is forced by the fuel pressure to axially move towardthe movable spring seat element 70 and has its stem portion 50 engagedat its leading end by the flange portion 72 of the spring seat element70. The force of the first pressure spring 64 urging the spring seatelement 70 toward the spacer element 14 is transmitted through thespring seat element 70 to the needle valve element 42 and urges theneedle valve element 42 to stay in an "initial" axial position closingthe fuel discharge passageway 22 in the nozzle member 12, opposing theforce of the fuel under pressure forcing the needle valve element 42 toaxially move in a direction to open the fuel discharge passageway 22 inthe needle valve element 42.

Within the nozzle holder 10 is further incorporated a push rod 76 havinga boss portion 78 and a rod portion 80 projecting from the boss portion78. The boss portion 78 of the push rod 76 is axially movable in thesecond spring chamber 56 and has one end face engageable with anadjustment shim 82 received on the other end face of the sleeve member60. The second pressure spring 66 provided in the second spring chamber56 is seated at one end on the other end face of the boss portion 78 ofthe push rod 76 and at the other end on an adjustment shim 84 receivedon a fixed spring seat element 86. The fixed spring seat element 86 issecured by a cap member 88 to the nozzle holder 10 at its end oppositeto the spacer element 14 as shown. The cap member 88 has an opening 90through which a plug member 92 is fitted to the cap member 88. The plugmember 92 has an axial bore 94 communicating with the second springchamber 56 in the nozzle holder 10 through an axial bore 96 in thespring seat element 86 and drain ports 98 sidewise leading from theaxial bore 94. The axial bore 94 and drain ports 98 thus formed in theplug member 92 allow leakage fuel out of the fuel injection valveassembly therethrough.

The rod portion 80 of the push rod 76 projects from the boss portion 78of the push rod 76 and extends through the axial bore 62 in the sleevemember 60 into the first spring chamber 54. The rod portion 80 extendstoward the lug portion 74 of the movable spring seat element 70 and hasan end face engageable with the end face of the lug portion 74 of thespring seat element 70. The second pressure spring 66 seated on the bossportion 78 of the push rod 76 urges the push rod 76 toward the lugportion 74 of the movable spring seat element 70 until the boss portion78 of the push rod 76 is received on the sleeve member 60 through theadjustment shim 82.

When the movable spring seat element 70 is engaged by the stem portion50 of the needle valve element 42 in the presence of fuel under pressurein the fuel discharge passageway 22 in the nozzle member 12, the springseat element 70 will be caused to move into engagement at the end of itsaxial lug portion 74 with the end face of the rod portion 80 of the pushrod 76. The force of the second pressure spring 66 urging the push rod76 toward the spring seat element 70 is transmitted through the push rod76 to the spring seat element 70 and further through the spring seatelement 70 to the needle valve element 42, thus further opposing theforce of the fuel under pressure forcing the needle valve element 42 toaxially move in the direction to open the fuel discharge passageway 22in the needle valve element 42. The needle valve element 42 moved in thedirection to open the fuel discharge passageway 22 in the nozzle member12 by the force of fuel under pressure is thus subjected first to theopposing force of the first pressure spring 64 and thereafter to theopposing forces of both of the first and second pressure springs 64 and66.

During each cycle of operation of the diesel engine, the fuel underpressure supplied from the fuel injection pump is admitted through thefuel feed pipe into the fuel passageway 34 in the connector 32 and isdirected through the fuel passageway 36 in the nozzle holder 10, theaperture 38 in the spacer element 14 and the fuel passageway 40 in thenozzle member 12 into the fuel discharge passageway 22 in the nozzlemember 12. The fuel pressure thus developed in the fuel dischargepassageway 22 in the nozzle member 12 acts on the needle valve element42 and forces the needle valve element 42 to axially move toward themovable spring seat element 70, that is, in the direction to open thefuel discharge passageway 22 in the needle valve element 42 until theneedle valve element 42 has its stem portion 50 engaged at its end bythe flange portion 72 of the spring seat element 70. The force of thefirst pressure spring 64 urging the movable spring seat element 70toward the spacer element 14 is transmitted through the spring seatelement 70 to the needle valve element 42 and opposes the force of thefuel under pressure acting on the needle valve element 42. The needlevalve element 42 is accordingly caused to move with the spring seatelement 70 against the force of the first pressure spring 64 until thelug portion 74 of the spring seat element 70 has its end face broughtinto pressing engagement with the end face of the rod portion 80 of thepush rod 76. The distance of movement of the needle valve element 42which is thus moved from its initial axial position to a first"critical" axial position having the movable spring seat element 70brought into pressing engagement with the rod portion 80 of the push rod76 provides the preliminary valve lift of the fuel injection valveassembly under consideration as indicated by PL in FIG. 2.

The needle valve element 42 being moved the distance providing thepreliminary valve lift PL, the fuel discharge passageway 22 in thenozzle member 12 is allowed to open so that the fuel which has beenpassed to the fuel discharge passageway 22 is discharged through thenozzle orifices 24 in the nozzle member 12 at a rate dictated by thepreliminary valve lift PL of the fuel injection valve assembly.

By the fuel pressure developed in the fuel discharge passageway 22 inthe nozzle member 12, the needle valve element 42 is caused to furthermove, now together with the push rod 76, in the direction to wider openthe fuel discharge passageway 22 in the nozzle member 12. The force ofthe fuel under pressure urging the needle valve element 42 to move inthis direction is now opposed by not only the force of the firstpressure spring 64 but also the force of the second pressure spring 66.The needle valve element 42 is thus caused to further move against theforces of the first and second pressure springs 64 and 66 until theguide portion 44 of the needle valve element 42 has its inner end facebrought into contact with the outer end face of the spacer element 14.The distance of movement of the needle valve element 42 which is thusmoved from its first critical axial position to a second "critical"axial position having the guide portion 44 thus brought into contactwith the spacer element 14 provides the full valve lift FL of the fuelinjection valve assembly under consideration as indicated by ML in FIG.2.

The needle valve element 42 being further moved the distance providingby the full valve lift FL, the fuel discharge passageway 22 in thenozzle member 12 is allowed to wider open so that the fuel in the fueldischarge passageway 22 in the nozzle member 12 is further dischargedthrough the nozzle orifices 24 in the nozzle member 12 at an increasedrate dictated by the full valve lift FL of the fuel injection valveassembly. The full valve lift FL of the fuel injection valve assembly isdefined as the sum of the preliminary valve lift PL and the full valvelift FL of the valve assembly as shown in FIG. 2.

As has been described, the prior-art fuel injection valve assembly ofthe two-stage opening type has two successive fuel discharge steps foreach cycle of operation of the associated power cylinder of the dieselengine. The quantity of fuel discharged from the nozzle member 12 intothe power cylinder during the first or earlier fuel discharge step isdictated by the preliminary valve lift PL of the fuel injection valveassembly, that is, the period of time for which the needle valve element42 is moved from the initial axial position to the first critical axialposition of the valve element 42. Likewise, the quantity of fueldischarged from the nozzle member 12 into the power cylinder during thesecond or later fuel discharge step is dictated by the full valve liftFL of the fuel injection valve assembly, that is, the period of time forwhich the needle valve element 42 is moved from the first critical axialposition to the second critical axial position of the valve element 42.

The various measurements of the fuel injection valve assembly that arepredominant over these periods of time, that is, the preliminary andmain valve lifts PL and ML of the valve assembly are selected so thatthe preliminary valve lift PL is smaller than the full valve lift FL.The preliminary valve lift PL is determined by the initial spacingbetween the end face of the lug portion 74 of the movable spring seatelement 70 and the end face of the rod portion 80 of the push rod 76 anddepends for its preciseness on the flatness and smoothness of each ofthese end faces of the spring seat element 70 and push rod 76, and thedegree of parallelism between the end faces of the spring seat element70 and push rod 76. The movable spring seat element 70 used in the shownprior-art fuel injection valve assembly being intricate in shape,extremely high techniques are required for controlling the dimensionalaccuracies of the spring seat element 70 and the associated members andelements during machining, assembling and adjusting of these members andelements to provide a preliminary valve lift PL with a satisfactorilyhigh degree of preciseness.

Various attempts have therefore been made to provide useful solutions tothis problem of the prior-art fuel injection valve of the describedconstruction. Examples of the prior-art fuel injection valves which haveresulted from these attempts are disclosed in the previously namedJapanese Provisional Utility Model Publications (Kokai) No. 56-173757and No. 61-184866. The prior-art fuel injection valve shown in each ofthese publications is characterized, inter alia, by the parallelarrangement of the first and second pressure springs providing thepreliminary and main valve lifts, respectively, of the valve assembly.The parallel arrangement of the two pressure springs is useful forreducing the number of members and elements which affect the degree ofaccuracy of, particularly, the preliminary valve lift and accordinglyfor alleviating the requirement for the extremely high techniques inmachining various members and elements of the fuel injection valveassembly.

The improvement achieved by the prior-art two-stage opening fuelinjection valve assembly taught in the Provisional Utility ModelPublication No. 56-173757 uses a movable spring seat element constantlyengaged by the needle valve element 42 and associated with one of thepressure springs arranged in parallel. The movable spring seat elementused in this prior-art fuel injection valve assembly is identical inshape to its counterpart in the fuel injection valve assemblyhereinbefore described with reference to FIGS. 1 and 2 and, for thisreason, the fuel injection valve assembly proposed by this publicationalso has the problem hereinbefore pointed out of the prior-art fuelinjection valve assembly shown in FIGS. 1 and 2 and is not fullyacceptable. The fuel injection valve assembly disclosed in thispublication further a drawback in that the needle valve element 42included therein could not be utilized without modification in a fuelinjection valve assembly of the type to which the present inventiongenerally appertains such as the prior-art valve assembly of FIGS. 1 and2.

On the other hand, the two-stage opening fuel injection valve assemblydisclosed in the Japanese Provisional Utility Model Publication No.61-184866 uses a fixed spring seat element common to both of thepressure springs arranged in parallel. The dimensional accuracy of thefixed spring seat element thus provided commonly to the two pressuresprings contributes to the degrees of preciseness of both of thepreliminary and main valve lifts. A dimensional error, if any, of thecommon fixed spring seat element would thus result in an error in eachof the preliminary and main valve lifts and would thus amplify the errorin the total valve lift which is given as the sum of the preliminary andmain valve lifts.

PREFERRED EMBODIMENTS OF THE INVENTION [First Preferred Embodiment](FIGS. 3 and 4)

FIGS. 3 and 4 show a first preferred embodiment of a two-stage openingfuel injection valve assembly to overcome these and other drawbacks of aprior-art two-stage opening fuel injection valve assembly.

The two-stage opening fuel injection valve assembly embodying thepresent invention as herein shown is in various respects similar inconstruction to the prior-art fuel injection valve assembly hereinbeforedescribed with reference to FIGS. 1 and 2. Thus, the two-stage openingfuel injection valve assembly embodying the present invention comprisesa valve casing structure composed of an elongated, generally cylindricalnozzle holder 10 and a nozzle member 12 projecting from the nozzleholder 10 through an annular spacer element 14. The annular spacerelement 14 thus axially intervening between the nozzle holder 10 andnozzle member 12 has opposite, parallel flat end faces which consist ofa first or inner end face 14a contiguous to the nozzle holder 10 and asecond or outer end face 14b contiguous to the nozzle member 12 asillustrated to an enlarged scale in FIG. 4. These inner and outer endfaces 14a and 14b of the spacer element 14 provide first and secondfixed internal surface portions, respectively, of a two-stage openingvalve assembly according to the present invention.

The nozzle member 12 has a generally cylindrical sleeve portion 16 and atip portion 18 axially projecting from the sleeve portion 16 in adirection opposite to the nozzle holder 10. The nozzle member 12 isformed with an axial valve chamber 20 extending in the sleeve portion 16and a fuel discharge passageway 22 extending longitudinally in the tipportion 18 of the nozzle member 12. The axial valve chamber 20 in thesleeve portion 16 terminates at the end of the nozzle member 12 close tothe outer end face 14b of the spacer element 14. The fuel dischargepassageway 22 in the tip portion 18 of the nozzle member 12 communicateswith the axial valve chamber 20 in the sleeve portion 16 and terminatesin nozzle orifices 24 located at the leading end of the tip portion 18.The nozzle member 12 is fastened to the nozzle holder 10 by means of aninternally threaded retaining nut member 26 fitted to an externallythreaded axial portion of the nozzle holder 10. During assembling of thefuel injection valve assembly herein shown, the nozzle holder 10, nozzlemember 12 and spacer element 14 are correctly positioned with respect toeach other by the aid of parallel locating pins 28 each having oppositeend portions fitted into the nozzle holder 10 and nozzle member 12,respectively, through the spacer element 14 as shown.

The nozzle holder 10 has a lateral lug portion 29 protruding sidewisefrom an intermediate axial portion of the nozzle holder 10 and hasformed therein an internally threaded axial bore 30. The axial bore 30has threadedly received therein an axial end portion of a connector 32formed with an axial fuel inlet passageway 34 extending between theopposite ends of the connector 32. The connector 32 is herein assumed toform part of the casing structure of the valve assembly underconsideration and connects the fuel injection valve assembly to a fuelfeed pipe leading from a source of high-pressure fuel typicallyimplemented by a fuel injection pump, though not shown in the drawings.High-pressure fuel is thus supplied from the fuel injection pump and isadmitted into the fuel injection valve assembly through the fuel inletpassageway 34 in the connector 32.

The nozzle holder 10 is formed with a fuel passageway 36 leading fromthe fuel inlet passageway 34 in the connector 32 to the end of thenozzle holder 10 close to the spacer element 14. The fuel passageway 36in the nozzle holder 10 terminates in an aperture 38 formed in thespacer element 14 so that the fuel directed into the fuel passageway 36in the nozzle holder 10 by way of the passageway 34 in the connector 32is passed through the aperture 38 in the spacer element 14 into a fuelpassageway 40 formed in the sleeve portion 16 of the nozzle member 12.The fuel passageway 40 thus formed in the sleeve portion 16 of thenozzle member 12 terminates in the fuel discharge passageway 22 in thetip portion 18 of the nozzle member 12. The fuel which has been passedto the fuel passageway 40 in the nozzle member 12 is thus dischargedthrough the nozzle orifices 24 in the tip portion 18 of the nozzlemember 12.

The nozzle member 12 has received therein a needle valve element 42having a cylindrical guide portion 44 and an elongated rod portion 46axially projecting from one end of the guide portion 44 in a directionopposite to the spacer element 14. The guide portion 44 of the needlevalve element 42 is axially slidable in the valve chamber 20 in thesleeve portion 16 of the nozzle member 12 and has a flat end face 44aparallel with and confronting the outer end face 14b of the spacerelement 14 as illustrated in FIG. 4. The rod portion 46 of the needlevalve element 42 axially extends through the fuel discharge passageway22 in the tip portion 18 of the nozzle member 12 and is needle-pointedtoward the leading end of the fuel discharge passageway 22 in the tipportion 18. The fuel discharge passageway 22 is thus closed or opened atits leading end by the pointed end of the rod portion 46 of the valveelement 42 as the valve element 42 is axially moved in the nozzle member12.

The needle valve element 42 further has a stem portion 50 axiallyprojecting from the opposite end of the guide portion 44 of the valveelement 42. The stem portion 50 of the needle valve element 42 extendsinto a central opening 52 formed in the spacer element 14 as illustratedto an ellarged scale in FIG. 4.

The nozzle holder 10 is formed with an axial bore extending from one endof the nozzle holder 10 to the other. The axial bore thus formed in thenozzle holder 10 has a bore portion forming a first spring chamber 56terminating at the end of the nozzle holder 10 remote from the spacerelement 14, and a bore portion forming a second spring chamber 54terminating at the opposite end of the nozzle holder 10 and axiallyaligned with the first spring chamber 56. It may be noted that the"first" and "second" spring chambers 56 and 54 of the nozzle holder 10forming part of the embodiment herein shown are referred to converselyto the first and second spring chambers 54 and 56 provided in the nozzleholder 10 of the prior-art fuel injection valve assembly described withreference to FIGS. 1 and 2. The axial bore in the nozzle holder 10further has an intermediate bore portion 58 axially intervening betweenthese first and second spring chambers 56 and 54 as shown.

In this intermediate bore portion 58 of the nozzle holder 10 is closelyreceived a cylindrical sleeve member 60 formed with an axial bore 62extending throughout the length of the sleeve member 60. The sleevemember 60 axially projects at one end into the first spring chamber 56and at the other into the second spring chamber 54. Thus, the sleevemember 60 provides at one end thereof a first fixed seat portionprojecting into the first spring chamber 56 and at the other end thereofa second fixed seat portion projecting into the second spring chamber 54of the nozzle holder 10.

In the first and second spring chambers 56 and 54 of the nozzle holder10 are incorporated first and second pressure springs 66 and 64,respectively, each in the form of a preloaded helical compressionspring. It may be noted that the "first" and "second" pressure springs66 and 64 of the embodiment herein shown are also referred to converselyto the first and second pressure springs 64 and 66 in the nozzle holder10 of the prior-art fuel injection valve assembly described withreference to FIGS. 1 and 2.

Within the nozzle holder 10 is further incorporated a push rod 76 havinga cylindrical boss portion 78 and an elongated rod portion 80 axiallyprojecting from the boss portion 78. The boss portion 78 of the push rod76 is axially movable in the first spring chamber 56 and has one endface engageable with an annular adjustment shim 82 received on the firstfixed seat portion of the sleeve member 60. The rod portion 80 of thepush rod 76 axially extends through the axial bore 62 in the sleevemember 60 into the second spring chamber 54 and has a flat end facedirected toward the spacer element 14 located axially opposite to thesleeve member 60.

The first pressure spring 66 provided in the first spring chamber 56 isseated at one end on one end face of the boss portion 78 of the push rod76 and at the other end on an annular adjustment shim 84 received on agenerally annular fixed spring seat element 86 fixedly positioned withinthe bore portion forming the spring chamber 56. The fixed spring seatelement 86 is secured to the nozzle holder 10 at its end opposite to thespacer element 14 by a generally cylindrical cap member 88. The capmember 88 has an end portion formed with an opening 90 through which aplug member 92 is fitted to the cap member 88. The plug member 92 has anaxial bore 94 communicating with the first spring chamber 56 in thenozzle holder 10 through an axial bore 96 in the spring seat element 86and drain ports 98 sidewise leading from the axial bore 94. The axialbore 94 and drain ports 98 thus formed in the plug member 92 andcommunicating with the first spring chamber 56 in the nozzle holder 10are provided to allow leakage fuel out of the fuel injection valveassembly therethrough. Between the end portion of the nozzle holder 10and the cap member 88 is provided a seal element 100 which hermeticallyseals off the spring chamber 56 to the cap member 88.

The axial stem portion 50 of the needle valve element 42 incorporated inthe embodiment herein shown is integral with or terminates inintervening means formed by a flange portion 102 which is larger indiameter than the stem portion 50 and which axially projects into thecentral opening 52 in the spacer element 14. Thus, the opening 52 in thespacer element 14 has a first axial portion accommodating the stemportion 50 of the needle valve element 42 and open to the axial valvechamber 20 in the sleeve portion 16 of the nozzle member 12 and a secondaxial portion accommodating the flange portion 102 of the needle valveelement 42 and open to the second spring chamber 54 in the nozzle holder10, as will be clearly seen in FIG. 4. The first axial portion of thevalve chamber 20 is smaller in diameter than the axial valve chamber 20in the sleeve portion 16 of the nozzle member 12, and the second axialportion of the valve chamber 20 is larger in diameter than the firstaxial portion of the valve chamber 20. The flange portion 102 of theneedle valve element 42 has a flat end face 102a directed toward andparallel with the inner flat end face 80a of the rod portion 80 of thepush rod 76 as illustrated in FIG. 4.

The rod portion 80 of the push rod 76 axially projects from the bossportion 78 of the push rod 76 and extends through the bore 62 in thesleeve member 60 into the second spring chamber 54. The rod portion 80extends toward and is aligned with the flange portion 102 of the needlevalve element 42 and has a flat end face 80a directed toward the endface 102a of the flange portion 102.

The second pressure spring 64 axially extends in the second springchamber 54 of the nozzle holder 10 and is seated at one end on anannular adjustment shim 68 received on the second fixed seat portion ofthe sleeve member 60. The second pressure spring 64 is seated at theother end on the inner end face of an annular movable spring seatelement 104 located close to the spacer element 14. The movable springseat element 104 has a flat end face 104a parallel with and confrontingthe inner end face 14a of the spacer element 14 and is urged by thesecond pressure spring 64 to have its end face 104a held in contact withthe end face 14a of the spacer element 14 as illustrated in FIG. 4. Themovable spring seat element 104 further has an axial bore 104b which isopen at the opposite ends of the spring seat element 104. The rodportion 80 of the push rod 76 axially extends toward the flange portion102 of the needle valve element 42 through this bore 104b in the movablespring seat element 104 and has its end face 80a engageable with the endface 102a of the flange portion 102 within the central opening 52 in thespacer element 14. In a fuel injection valve assembly according to thepresent invention, the movable spring seat element 104 implements afirst movable member while the push rod 76 implements a second movablemember.

The fuel injection valve assembly constructed as hereinbefore describedis fitted into one of the power cylinders of a diesel engine with asuitable axial portion such as the axial portion indicated at 10a of thenozzle holder 10 screwed through the cylinder head of the engine, thoughnot shown in the drawings.

The first pressure spring 66 incorporated in the first spring chamber 56and engaging the push rod 76 urges the push rod 76 toward the flangeportion 102 of the needle valve element 42 until the boss portion 78 ofthe push rod 76 is received on the first seat portion of the sleevemember 60 across the annular adjustment shim 82. In the presence of fuelunder pressure in the fuel discharge passageway 22 in the nozzle member12, the needle valve element 42 is forced by the fuel pressure toaxially move toward the movable spring seat element 104 in the secondspring chamber 54. Thus, the flange portion 102 of the needle valveelement 42 has its end face 102a brought into contact with the end face80a of the rod portion 80 of the push rod 76 so that the force of thefirst pressure spring 66 urging the push rod 76 toward the needle valveelement 42 is transmitted through the push rod 76 to the needle valveelement 42 and opposes the force of the fuel under pressure acting onthe needle valve element 42. The needle valve element 42 is accordinglyheld in an initial axial position closing the fuel discharge passageway22 in the nozzle member 12. This initial axial position of the needlevalve element 42 is maintained with an equilibrium established betweenthe force of the first spring 66 acting on the push rod 76 and the forceresulting from the fuel pressure acting on the needle valve element 42.The guide portion 44 of the needle valve element 42 held in the initialaxial position has its end face 44a spaced apart a predetermineddistance from the outer end face 14b of the spacer element 14. Thedistance between the outer end face 14b of the spacer element 14 and theend face 44a of the guide portion 44 of the needle valve element 42 heldin the initial axial position defines the amount of full valve lift FLof the fuel injection valve assembly herein shown. Furthermore, thedistance between the end face 102a of the flange portion 102 of theneedle valve element 42 held in the initial axial position and the endface 104a of the movable spring seat element 104 seated on the inner endface 14a of the spacer element 14 defines the amount of preliminaryvalve lift PL of the fuel injection valve assembly herein shown.

When the force resulting from the fuel pressure acting on the needlevalve element 42 overcomes the opposing force of the first pressurespring 66, the needle valve element 42 is caused to axially move fromits initial axial position in a direction to open the fuel dischargepassageway 22 in the nozzle member 12 until the needle valve element 42reaches a first critical axial position having the end face 102a of itsflange portion 102 brought into contact with the end face 104a of themovable spring seat element 104. The guide portion 44 of the needlevalve element 42 held in the first critical axial position has its endface 44a spaced apart a predetermined distance from the outer end face14b of the spacer element 14. The distance between the outer end face14b of the spacer element 14 and the end face 44a of the guide portion44 of the needle valve element 42 thus held in the first critical axialposition defines the amount of full valve lift FL of the fuel injectionvalve assembly herein shown. Furthermore, the movement of the needlevalve element 42 from the initial axial position to the first criticalaxial position provides the preliminary valve lift PL of the fuelinjection valve assembly as has been noted. The amount of preliminaryvalve lift PL of the fuel injection valve assembly embodying the presentinvention can thus be adjusted by varying the thickness of the spacerelement 14 to increase or decrease the spacing between the end face 104aof the movable spring seat element 104 seated on the spacer element 14and the end face 102a of the flange portion 102 of the needle valveelement 42 in the initial axial position thereof.

The second pressure spring 64 incorporated in the second spring chamber54 and seated on the movable spring seat element 104 urges the springseat element 104 to rest on the inner end face 14a of the spacer element14. In the presence of fuel under pressure in the fuel dischargepassageway 22 in the nozzle member 12 after the needle valve element 42has been moved to the first critical axial position, the needle valveelement 42 is caused to further move from the particular position andcauses the movable spring seat element 104 to move away from the innerend face 14a of the spacer element 14. The needle valve element 42 beingengaged by the spring seat element 104, the force of the second pressurespring 64 is transmitted through the movable spring seat element 104 tothe needle valve element 42 so that the axial movement of the needlevalve element 42 in the direction to open the fuel discharge passageway22 is opposed by the force of the second pressure spring 64 in additionto the force of the first pressure spring 66. The needle valve element42 is thus caused to move from the first critical position against theforces of the first and second pressure springs 66 and 64 until theneedle valve element 42 reaches a second critical axial position havingthe end face 44a of its guide portion 44 brought into contact with theouter end face 14b of the spacer element 14. As has been noted, themovement of the needle valve element 42 from the first critical axialposition to this second critical axial position provides the full valvelift FL of the fuel injection valve assembly.

From the above description it will have been understood that the needlevalve element 42 moved from the initial axial position in the directionto open the fuel discharge passageway 22 in the nozzle member 12 isfirst subjected to the opposing force of the first pressure spring 66alone and thereafter undergoes the opposing forces of both of the firstand second pressure springs 66 and 64. More specifically, the needlevalve element 42 is subjected to the opposing force of the firstpressure spring 66 during its movement from the initial axial positionto the first critical axial position and to the opposing forces of thefirst and second pressure springs 66 and 64 during its movement from thefirst critical axial position to the second critical axial positionthereof.

The operation of the two-stage opening fuel injection valve assemblythus constructed and arranged in accordance with the present inventionwill now be described in detail.

During each cycle of operation of the diesel engine, the fuel underpressure supplied from the fuel injection pump is admitted through thefuel feed pipe into the fuel inlet passageway 34 in the connector 32 andis directed through the fuel passageway 36 in the nozzle holder 10, theaperture 38 in the spacer element 14 and the fuel passageway 40 in thenozzle member 12 into the fuel discharge passageway 22 in the tipportion 18 of the nozzle member 12. The fuel pressure thus developed inthe fuel discharge passageway 22 in the nozzle member 12 acts on theneedle valve element 42 which has been held in the initial axialposition thereof and forces the needle valve element 42 to axially movetoward the movable spring seat element 104 seated on the inner end face14a of the spacer element 14. The needle valve element 42 being engagedby the push rod 76 with the end face 102a of its flange portion 102contacted by the end face 80a of the rod portion 80 of the push rod 76,the axial movement of the needle valve element 42 from the initial axialposition is opposed by the force of the first pressure spring 66transmitted through the push rod 76 to the needle valve element 42. Theneedle valve element 42 is thus caused to move with the push rod 76against the force of the first pressure spring 66 until the needle valveelement 42 reaches the first critical axial position having the end face102a of its flange portion 102 brought into pressing engagement with theend face 104a of the movable spring seat element 104. As has been noted,the distance of movement of the needle valve element 42 which is thusmoved from the initial axial position to the first critical axialposition provides the preliminary valve lift PL of the fuel injectionvalve assembly. The needle valve element 42 being thus moved thedistance providing the preliminary valve lift PL, the fuel dischargepassageway 22 in the nozzle member 12 is allowed to open so that thefuel which has been passed to the fuel discharge passageway 22 isdischarged through the nozzle orifices 22 in the nozzle member 12 at arate dictated by the preliminary valve lift PL of the fuel injectionvalve assembly.

By the fuel pressure developed in the fuel discharge passageway 22 inthe nozzle member 12, the needle valve element 42 is caused to furthermove, now together with the movable spring seat element 104, in thedirection to wider open the fuel discharge passageway 22 in the nozzlemember 12. The force of the fuel under pressure urging the needle valveelement 42 to move in this direction is now opposed not only by theforce of the first pressure spring 66 but also by the force of thesecond pressure spring 64. The needle valve element 42 is thus caused tofurther move from its first critical axial position against the forcesof the first and second pressure springs 66 and 64 until the needlevalve element 42 reaches the second critical axial position having theend face 44a of its guide portion 44 brought into contact with the outerend face 14b of the spacer element 14. The distance of movement of theneedle valve element 42 which is thus moved from the first criticalaxial position to the second critical axial position having the guideportion 44 thus brought into contact with the spacer element 14 providesthe full valve lift FL of the fuel injection valve assembly as has beennoted. The needle valve element 42 being thus further moved the distanceproviding the full valve lift FL, the fuel discharge passageway 22 inthe nozzle member 12 is allowed to wider open so that the fuel in thefuel discharge passageway 22 is discharged through the nozzle orifices22 in the nozzle member 12 at an increased rate dictated by the fullvalve lift FL of the fuel injection valve assembly.

The first preferred embodiment of the present invention as has beendescribed hereinbefore is advantageous over the prior-art fuel injectionvalve assembly of FIGS. 1 and 2 in that the flange portion 102 of theneedle valve element 42 is simpler in shape than the movable spring seatelement 70 used in the prior-art valve assembly. The fuel injectionvalve assembly embodying the present invention can thus be fabricatedwith the preliminary valve lift PL defined to a desired degree ofpreciseness more easily and at a lower cost than in the case of theprior-art fuel injection valve assembly.

As has been noted, the fuel injection valve assembly embodying thepresent invention is fitted into a power cylinders of a diesel enginewith the axial portion 10a of the nozzle holder 10 screwed through andtightened to the cylinder head of the engine. A stress is created in theaxial portion 10a of the nozzle holder 10 and would cause a change inthe longitudinal measurement of the nozzle holder 10 after the valveassembly is fitted to the engine power cylinder. The axial portion ofthe nozzle holder 10 accommodating the first pressure spring 66contributing to the formation of the preliminary valve lift PL extendsoutwardly of the cylinder head to which the fuel injection valveassembly is secured and is therefore isolated from the stress created inthe axial portion 10a. The amount of preliminary valve lift PL of thefuel injection valve assembly is for this reason practically free fromthe influence of the stress caused in the axial portion 10a of thenozzle holder 10 so that the preciseness of the preliminary valve liftPL set up during fabrication of the fuel injection valve assembly can bemaintained substantially throughout use of the valve assembly.

[Second Preferred Embodiment] (FIG. 5)

FIG. 5 shows a second preferred embodiment of a two-stage opening fuelinjection valve assembly proposed by the present invention.

The embodiment of the present invention herein shown is a modificationof the two-stage opening fuel injection valve assembly hereinbeforedescribed with reference to FIGS. 3 and 4. The fuel injection valveassembly shown in FIG. 5 is similar in construction to the valveassembly of FIGS. 3 and 4 except in that a flange member 106 whichimplements intervening means in the embodiment herein shown is providedin substitution for the flange portion 102 of the needle valve element42 used in the embodiment of FIGS. 3 and 4. While the flange portion 102of the needle valve element 42 incorporated in the embodiment of FIGS. 3and 4 is part of the needle valve element 42 per se, the flange member106 used in the embodiment herein shown is formed separately of theneedle valve element 42 and is held in engagement with the stem portion50 of the needle valve element 42. This flange member 106 is provided inthe form of a disc member having a flat end face 106a identical with theend face 102a of the flange portion 102 of the needle valve element 42in the embodiment of FIGS. 3 and 4. The flange member 106 further has acircular concavity 108 which is shaped conformingly to a leading endportion of the stem portion 50 of the needle valve element 42 as shown.Thus, the stem portion 50 of the needle valve element 42 fuel injectionvalve assembly has its leading end portion snugly received in thecircular concavity 108 in the flange member 106 so that the flangemember 106 acts similarly to the flange portion 102 of the needle valveelement 42 in the embodiment of FIGS. 3 and 4 with respect to themovable spring seat element 104 and the rod portion 80 of the push rod76. If desired, the flange member 106 may be secured to the needle valveelement 42 by means of any adhesive or by mechanical fastening meanssuch as a screw or a stud, though not shown in the drawings.

In the embodiment of FIG. 5, the preliminary valve lift PL of the valveassembly is defined between the end face 106a of the flange member 106attached to the needle valve element 42 held in the initial axialposition and the end face 104a of the movable spring seat element 104seated on the inner end face 14a of the spacer element 14. The fullvalve lift FL is defined between the end face 44a of the guide portion44 of the needle valve element 42 in the initial axial position and theouter end face 14b of the spacer element 14. The full valve lift FL ofthe valve assembly is defined between the outer end face 14b of thespacer element 14 and the end face 44a of the guide portion 44 of theneedle valve element 42 moved to the first critical axial positionthereof.

The embodiment of the present invention illustrated in FIG. 5 isadvantageous over the embodiment of FIGS. 3 and 4 in that the needlevalve element 42 used in the former is per se similar to that used inthe prior-art valve assembly hereinbefore described with reference toFIGS. 1 and 2. Thus, the needle valve element 42 fabricated for use inthe prior-art valve assembly can be utilized without modification as theneedle valve element 42 in the fuel injection valve assembly illustratedin FIG. 5. Another advantage of the fuel injection valve assembly shownin FIG. 5 is that the amount of preliminary valve lift PL can be readilyvaried through selection of the thickness of the flange member 106 whichis formed separately of the needle valve element 42.

[Third Preferred Embodiment] (FIGS. 6 and 7)

FIGS. 6 and 7 show a third preferred embodiment of a two-stage openingfuel injection valve assembly proposed by the present invention.

The embodiment of the present invention herein shown is anothermodification of the two-stage opening fuel injection valve assemblyhereinbefore described with reference to FIGS. 3 and 4. The fuelinjection valve assembly herein shown is further similar to theembodiment of FIG. 5 in that a flange member, now represented byreference numeral 110, is provided as intervening means in substitutionfor the flange portion 102 of the needle valve element 42 used in theembodiment of FIGS. 3 and 4 and is formed separately of the needle valveelement 42. The flange member 110 used in the embodiment herein shown isthus also held in engagement with the stem portion 50 of the needlevalve element 42 or may be secured to the needle valve element 42 bymeans of any adhesive or by mechanical fastening means such as a screwor a stud. The flange member 110 has an end face 110a opposite to thestem portion 50 of the needle valve element 42 and is formed with acircular concavity 110b in which is closely received a leading endportion of the stem portion 50 of the needle valve element 42.

In the embodiment shown in FIGS. 6 and 7, the flange member 110 engagedby or secured to the stem portion 50 of the needle valve element 42 hasa hemispherically dished concavity 110c which is axially open at its endface 110a opposite to the stem portion 50 of the needle valve element 42as illustrated to an enlarged scale in FIG. 7. The concavity 110c may bepress forged into the flange member 110. The rod portion 80 of the pushrod 76 has a rounded end portion 112 shaped conformingly to thehemispherical concavity 110c and slidably received in the concavity110c. The needle valve element 42, flange member 110 and push rod 76have respective center axes aligned with each other so that, when thepush rod 76 or, particularly, the rod portion 80 of the push rod 76happens to incline with respect to the flange member 110 during itsaxial movement in the nozzle holder 10, the inclination of the push rod76 or the rod portion thereof is taken up by the sliding movement of therounded end portion of the rod portion 80. The flange member 110 is thusprevented from being inclined with respect to the movable spring seatelement 104 and is enabled to maintain its correct position with respectto the spring seat element 104 so that the initial degree of precisenessof, particularly, the preliminary valve lift PL of the valve assemblycan be maintained throughout use of the valve assembly.

In the embodiment shown in FIGS. 6 and 7, furthermore, the bore portionforming the first spring chamber 56 in the nozzle holder 10 issignificantly longer than the bore portion forming the second springchamber 54 in the nozzle holder 10. In substitution for the fixed springseat element 86 incorporated in the bore portion forming the firstspring chamber 56 in the nozzle holder 10 of the embodiment of FIGS. 3and 4 or the embodiment of FIG. 5 is provided a generally cylindricalexternally threaded member fixedly fitted into the bore portion formingthe spring chamber 56 to implement an adjustment screw 114. Theadjustment screw 114 has an externally threaded axial portion engaged byan internally threaded axial portion of the nozzle holder 10 asindicated at 116 in FIG. 6 and is secured to the nozzle holder 10 at itsend opposite to the spacer element 14 by means of a cap member 88. As inthe embodiment described with reference to FIGS. 3 and 4, the cap member88 has an end portion formed with an opening 90 through which a plugmember 92 is fitted to the cap member 88. The plug member 92 has anaxial bore 94 communicating with the first spring chamber 56 in thenozzle holder 10 through an axial bore 118 formed in the adjustmentscrew 114 and extending throughout the length of the screw 114. The pushrod 76 extending into the first spring chamber 56 in the embodimentherein shown has a flange portion 78' in lieu of the boss portion 78 ofthe push rod 76 in each of the described first and second embodiments ofthe present invention. Furthermore, the sleeve member 60 extendingbetween the first and second spring chambers 56 and 54 through the boreportion 58 of the nozzle holder 10 in each of the first and secondembodiments of the present invention is dispensed with in the embodimentherein shown. Thus, the elongated rod portion 80 of the push rod 76axially projects from the flange portion 78' of the push rod 76 andextends directly through the axial bore portion 58 in the nozzle holder10 into the second spring chamber 54.

The adjustment screw 114 has an axial end portion projecting into thefirst spring chamber 56 to form an annular spring seat portion 114aaround the end portion. The first pressure spring 66 provided in thefirst spring chamber 56 is seated at one end on one end face of theflange portion 78 of the push rod 76 and at the other end on the flangeportion 78' of the push rod 76. The force of the pressure spring 66 thusextending longitudinally in the first spring chamber 56 in a preloadedstate is thus determined by the length to which the adjustment screw 114projects into the spring chamber 56 and can be readily adjusted byvarying the length to which the screw 114 is threadedly fitted into thenozzle holder 10.

In the embodiment of FIGS. 6 and 7, the preliminary valve lift PL of thevalve assembly is also defined between the end face 110a of the flangemember 110 attached to the needle valve element 42 held in the initialaxial position and the end face 104a of the movable spring seat element104 seated on the inner end face 14a of the spacer element 14. The fullvalve lift FL is defined between the and face 44a of the guide portion44 of the needle valve element 42 in the initial axial position and theouter end face 14b of the spacer element 14. The full valve lift FL ofthe valve assembly is defined between the outer end face 14b of thespacer element 14 and the end face 44a of the guide portion 44 of theneedle valve element 42 moved to the first critical axial positionthereof.

It will have been understood from the foregoing description that theembodiment of the present invention hereinbefore described withreference to FIGS. 6 and 7 is characterized inter alia by the slidableengagement between the rounded end portion of the rod portion 80 of thepush rod 76 and the helispherically dished concavity 110c in the movablespring seat element 104. By reason of such engagement between the pushrod 76 and movable spring seat element 104, the flange member 110intervening between the needle valve element 42 and push rod 76 isallowed to maintain its correct position with respect to the spring seatelement 104 so that the initial degree of preciseness of, particularly,the preliminary valve lift PL of the valve assembly is maintainedthroughout use of the valve assembly. The embodiment of FIGS. 6 and 7 isfurther advantageous in that the needle valve element 42 used in thevalve assembly is per se also similar to that used in the prior-artvalve assembly hereinbefore described with reference to FIGS. 1 and 2and, for this reason, the needle valve element 42 fabricated for use inthe prior-art valve assembly can be utilized without modification in thefuel injection valve assembly of FIGS. 6 and 7. Another advantage of thefuel injection valve assembly shown in FIGS. 6 and 7 is that the amountof preliminary valve lift PL can be readily varied through selection ofthe thickness of the flange member 110 which is formed separately of theneedle valve element 42.

[Fourth Preferred Embodiment] (FIGS. 8 and 9)

FIGS. 8 and 9 show a fourth preferred embodiment of a two-stage openingfuel injection valve assembly proposed by the present invention. Theembodiment of the present invention herein shown is also a modificationof the two-stage opening fuel injection valve assembly hereinbeforedescribed with reference to FIGS. 3 and 4.

In the embodiment herein shown, the flange member, now represented byreference numeral 120, has an axial bore 122 which is open at theopposite ends of the flange member 120 and has the stem portion 50 ofthe needle valve element 42 securely received in the bore 122. The stemportion 50 of the needle valve element 42 thus axially extends throughthe axial bore 122 in the flange member 120 and projects into the secondspring chamber 54 or, more specifically, into the axial bore 104b in themovable spring seat element 104 as shown. Thus, the needle valve element42 is constantly engaged by the push rod 76 with the end face 50a of itsstem portion 102 held in contact with the end face 80a of the rodportion 80 of the push rod 76 by the force of the first pressure spring64 and the fuel under pressure in the fuel discharge passageway 22 inthe nozzle member 12.

The spacer element 14 incorporated in the embodiment of FIGS. 8 and 9has in addition to the circular central opening 52 a plurality of grooveportions 124 radially merging outwardly out of the central opening 52and arranged at equal angles with respect to each other about the centeraxis of the opening 52 as will be better seen from FIG. 9. The flangemember 120 engaging the spacer element 14 accordingly has a generallycylindrical or disc-shaped center portion 126 formed with the axial bore122 and and a plurality of radial limb portions 128 radially protrudingfrom the center portion 126. The center portion 126 of the flange member120 is slidably received in the central opening 52 in the spacer element14 and the radial limb portions 128 of the flange member 120 arerespectively received in the groove portions 124 in the spacer element14.

The center portion 126 of the flange member 120 has an outside diametersmaller than the diameter of the second spring chamber 54 and has a flatend face 126a parallel with and confronting the end face 104a of themovable spring seat element 104. Each of the radial limb portions 128 ofthe flange member 120 extend in proximity to the flat end face 10b whichthe nozzle holder 10 has adjacent to the inner end face 14a of thespacer element 14 and has a flat end face 128a parallel with andconfronting the end face 10b of the nozzle holder 10 as shown in FIG. 8.The end face 128a of each of the radial limb portions 128 of the flangemember 120 is lower than the end face 126a of the center portion 126 ofthe flange member 120 or, in other words, the plane defined by the endface 128a of each limb portion 128 is spaced apart more from the planedefined by the inner end face 14a of the spacer element 14 than theplane defined by the end face 126a of the center portion 126 of theflange member 120. Thus, the flange member 120 provided in theembodiment herein shown has a first end face implemented by the end face126 of its center portion 126 and a second end face implemented by theend face 128a of each of its radial limb portions 128 and lower than thefirst end face.

In operation, the fuel under pressure developed in the fuel dischargepassageway 22 in the nozzle member 12 acts on the needle valve element42 held in the initial axial position thereof and forces the needlevalve element 42 to axially move toward the movable spring seat element104 seated on the inner end face 14a of the spacer element 14 by theforce of the second pressure spring 66. The needle valve element 42being engaged by the push rod 76 with the end face 50a of its stemportion 102 contacted by the end face 80a of the rod portion 80 of thepush rod 76, the axial movement of the needle valve element 42 from theinitial axial position is opposed by the force of the first pressurespring 66 transmitted through the push rod 76 to the needle valveelement 42. The needle valve element 42 is thus caused to move with thepush rod 76 against the force of the first pressure spring 66 until theneedle valve element 42 reaches a first critical axial position havingthe end face 126a of its flange member 120 brought into pressingengagement with the end face 104a of the movable spring seat element104. The distance of movement of the needle valve element 42 which isthus moved from the initial axial position to the first critical axialposition provides the preliminary valve lift PL of the fuel injectionvalve assembly under consideration. The needle valve element 42 beingthus moved the distance providing the preliminary valve lift PL, thefuel discharge passageway 22 in the nozzle member 12 is allowed to openso that the fuel which has been passed to the fuel discharge passageway22 is discharged through the nozzle orifices 22 in the nozzle member 12at a rate dictated by the preliminary valve lift PL of the fuelinjection valve assembly.

By the fuel pressure developed in the fuel discharge passageway 22 inthe nozzle member 12, the needle valve element 42 is caused to furthermove, now together with the movable spring seat element 104, in thedirection to wider open the fuel discharge passageway 22 in the nozzlemember 12. The force of the fuel under pressure urging the needle valveelement 42 to move in this direction is now opposed not only by theforce of the first pressure spring 66 but by the force of the secondpressure spring 64. The needle valve element 42 is thus caused tofurther move from its first critical axial position against the forcesof the first and second pressure springs 66 and 64 until the needlevalve element 42 reaches a second critical axial position having therespective end faces 128a of the radial limb portions 128 of the flangemember 120 brought into contact with the end face 10b of the nozzleholder 10. The distance of movement of the needle valve element 42 whichis thus moved from the first critical axial position to the secondcritical axial position having the radial limb portions 128 of theflange member 120 thus brought into contact with the end face 10b of thenozzle holder 10 provides the full valve lift FL of the fuel injectionvalve assembly under consideration. The needle valve element 42 beingthus further moved the distance providing the full valve lift FL, thefuel discharge passageway 22 in the nozzle member 12 is allowed to wideropen so that the fuel in the fuel discharge passageway 22 is dischargedthrough the nozzle orifices 22 in the nozzle member 12 at an increasedrate dictated by the full valve lift FL of the fuel injection valveassembly.

From the above description it will have been understood that thepreliminary valve lift PL of the valve assembly implementing the fourthpreferred embodiment of the present invention is defined between thefirst end face 126a of the flange member 120 fixedly engaging the needlevalve element 42 held in the initial axial position and the end face104a of the movable spring seat element 104 seated on the inner end face14a of the spacer element 14. The full valve lift FL is defined betweenthe second end faces 128a of the flange member 120 engaging the needlevalve element 42 in the initial axial position and the end face 10b ofthe nozzle holder 10 or, in other words, a plane defined by the innerend face 14a of the spacer element 14. The full valve lift FL of thevalve assembly is defined between the end face 104a of the movablespring seat element 104 and the second end faces 128a of the flangemember 120 engaging the needle valve element 42 moved to the firstcritical axial position thereof.

The fourth preferred embodiment of the present invention as has beendescribed hereinbefore is also advantageous over the prior-art fuelinjection valve assembly of FIGS. 1 and 2 in that the flange member 120fixedly engaging the needle valve element 42 is simpler in shape thanthe movable spring seat element 70 used in the prior-art valve assembly.The fuel injection valve assembly embodying the present invention canthus be fabricated with the preliminary valve lift PL defined to adesired degree of preciseness more easily and at a lower cost than inthe case of the prior-art fuel injection valve assembly.

What is claimed is:
 1. A two-stage opening fuel injection valveassembly, comprising(a) a valve element having an initial positionproviding a substantially zero flow rate of fuel through the valveassembly, a first critical position displaced a first predetermineddistance from the initial position in a predetermined direction andproviding a first flow rate of fuel through the valve assembly, a secondcritical position further displaced a second predetermined distance fromthe first critical position in said predetermined direction andproviding a second flow rate of fuel through the valve assembly, (b)first and second movable members which are engageable with said valveelement independently of each other, (c) intermediate means constantlyengaged by said valve element and engageable with each of said first andsecond movable members, (d) first biasing means urging said firstmovable member toward a predetermined position to engage saidintermediate means when said valve element is held in said initialposition, the first biasing means being operative to maintain theengagement between said first movable member and said intermediate meanswhen the valve element is located between said initial position and saidfirst critical position, (e) second biasing means urging said secondmovable member toward a predetermined position to engage saidintermediate means when said valve element is moved from said initialposition to one of said first and second critical positions, the secondbiasing means being operative to maintain the engagement between saidsecond movable member and said intermediate means when the valve elementis located between said first and second critical positions, and (f)displacement limiting means preventing movement of said valve elementbeyond said second critical position in said predetermined direction. 2.A two-stage opening fuel injection valve assembly as set forth in claim1, in which said second biasing means urges said second movable membertoward said predetermined position to engage said intermediate meanswhen said valve element is held in said first critical position.
 3. Atwo-stage opening fuel injection valve assembly as set forth in claim 1,in which said second biasing means urges said second movable membertoward said predetermined position to engage said intermediate meanswhen said valve element is held in said second critical position.
 4. Atwo-stage opening fuel injection valve assembly as set forth in claim 1,in which said intermediate means comprises a portion of said valveelement.
 5. A two-stage opening fuel injection valve assembly as setforth in claim 1, in which said intermediate means comprises a flangemember formed separately of and constantly engaged by said valveelement, said flange member being located between said valve element andsaid first movable member.
 6. A two-stage opening fuel injection valveassembly as set forth in claim 5, in which said flange member has asubstantially hemispherically dished concavity which is open toward saidfirst movable member and which has a center axis substantially parallelwith said predetermined direction, said first movable member having agenerally hemispherically rounded end portion slidably received in saidconcavity.
 7. A two-stage opening fuel injection valve assembly as setforth in claim 1, in which said intermediate means comprises a flangemember formed separately of and constantly engaged by said valveelement, said flange member having a bore through which said valveelement is engageable with said first movable member, a first end facespaced apart said first predetermined distance from said second movablemember when said valve element is held in said initial position, asecond end face spaced apart the sum of said first and secondpredetermined distances from said second movable member when said valveelement is held in said initial position.
 8. A two-stage opening fuelinjection valve assembly having a full valve lift and a preliminaryvalve lift which forms part of the full valve lift, comprising(a) acasing structure having formed therein a fuel passageway into which isto be directed fuel under pressure, a substantially flat fixed internalsurface portion, and first and second chambers arranged in series witheach other perpendicularly to said fixed internal surface portion, (b)first and second biasing means provided in said first and secondchambers, respectively, (c) a first movable member movable in partwithin said first chambers and in part within said second chambers, (d)a second movable member movable within said second chambers and locatedin the vicinity of the end of the second chambers opposite to the firstchamber, said second movable member having an end face substantiallyparallel with and confronting said fixed internal surface portion, saidsecond biasing means constantly engaging said second movable member forurging the second movable member into contact with said fixed internalsurface portion, (e) a valve element located in the vicinity of saidsecond movable member and movable toward and away from the secondmovable member for controlling the flow rate of fuel through said fuelpassageway, (f) said first movable member being constantly engaged bysaid first biasing means and said valve element in the presence of fuelpressure in said fuel passageway for transmitting from the first biasingmeans to the valve element a force urging the valve element toward apredetermined initial position with respect to the second movable memberheld in contact with said fixed internal surface portion, and (g)intermediate means intervening between said first movable member andsaid valve element, the intermediate means being movable with said valveelement and having an end face substantially parallel with and locatedadjacent to the end face of said second movable member, (h) the distancebetween the end face of said second movable member and the end face ofthe intermediate means engaging the valve element held in said initialposition defining the amount of said preliminary valve lift.
 9. Atwo-stage opening fuel injection valve assembly as set forth in claim 8,in which said fixed internal surface portion is one of first and secondfixed internal surface portions formed in said casing structure andsubstantially parallel with each other and is constantly contacted bysaid second movable member and in which said valve element has an endface substantially parallel with and located adjacent said second fixedinternal surface portion, the distance between said second fixedinternal surface portion and the end face of the valve element held insaid initial position defining the amount of said full valve lift.
 10. Atwo-stage opening fuel injection valve assembly as set forth in claim 9,in which said casing structure comprises a nozzle holder having saidfirst and second chambers formed therein, a nozzle member having saidfuel passageway formed therein and a spacer element intervening betweenthe nozzle holder and the nozzle member and having formed therein anopening through which said valve element is held in engagement with saidfirst movable member in the presence of fuel pressure in said fuelpassageway, said spacer element having first and second end facessubstantially parallel with the end face of said second movable member,said first end face of said spacer element forming said first fixedinternal surface portion and being located adjacent to said end face ofsaid second movable member, said second end face of said spacer elementforming said second fixed internal surface portion and beingsubstantially parallel with and located adjacent to said end face of thevalve element held in said initial position.
 11. A two-stage openingfuel injection valve assembly as set forth in claim 9, in which saidintermediate means comprises a portion of said valve element, saidportion of said valve element being movable within said opening in saidspacer element and being held in engagement with said first movablemember through said opening.
 12. A two-stage opening fuel injectionvalve assembly as set forth in claim 9, in which said intermediate meanscomprises a flange member formed separately of and constantly engagingsaid valve element and having an end face substantially parallel withand located adjacent to the end face of said second movable member andforming said end face of said intermediate means.
 13. A two-stageopening fuel injection valve assembly as set forth in claim 12, in whichsaid flange member has formed therein a substantially hemisphericallydished concavity which is open at a plane defined by the end face ofsaid flange member, said first movable member having a generallyhemispherically rounded end portion slidably received in said concavityin the presence of fuel under pressure in said fuel passageway.
 14. Atwo-stage opening fuel injection valve assembly as set forth in claim 8,in which said intermediate means comprises a flange member formedseparately of and securely engaged by said valve element and having abore through which said valve element is held in engagement with saidfirst movable member in the presence of fuel pressure in said fuelpassageway, said flange member having a first end face defining a planesubstantially parallel with and located adjacent to a plane defined bysaid fixed internal surface portion and a second end face defining aplane substantially parallel with the plane defined by said first endface and spaced apart more from the plane defined by said fixed internalsurface portion than the plane defined by said first end face, thedistance between the plane defined by said fixed internal surfaceportion and the plane defined by the first end face of the flange memberengaging the valve element held in said initial position defining theamount of said preliminary valve lift, and the distance between theplane defined by said fixed internal surface portion and the planedefined by the second end face of the flange member engaging the valveelement held in said initial position defining the amount of said fullvalve lift.
 15. A two-stage opening fuel injection valve assembly as setforth in claim 8, in which said casing structure comprises a nozzleholder having said first and second chambers formed therein, a nozzlemember having said fuel passageway formed therein and a spacer elementintervening between the nozzle holder and nozzle member and havingformed therein an opening through which said valve element is held inengagement with said first movable member in the presence of fuelpressure in said fuel passageway, said spacer element having an end facesubstantially parallel with and located adjacent to the end face of saidsecond movable member, said fixed internal surface portion being formedby said end face of said spacer element.
 16. A two-stage opening fuelinjection valve assembly as set forth in claim 15, in which saidintermediate means comprises a flange member formed separately of andsecurely engaged by said valve element and having a bore through whichsaid valve element is held in engagement with said first movable memberin the presence of fuel pressure in said fuel passageway, said flangemember having a first end face defining a plane substantially parallelwith and located adjacent to a plane defined by said end face of saidspacer element and a second end face defining a plane substantiallyparallel with the plane defined by said first end face and spaced apartmore from the plane defined by said first end face than the planedefined by said first end face, the distance between the plane definedby said end face of said spacer element and the plane defined by thefirst end face of the flange member engaging the valve element held insaid initial position defining the amount of said preliminary valvelift, and the distance between the plane defined by said end face ofsaid spacer element and the plane defined by the second end face of theflange member engaging the valve element held in said initial positiondefining the amount of said full valve lift.
 17. A two-stage openingfuel injection valve assembly having a full valve lift and a preliminaryvalve lift which forms part of the full valve lift, comprising(a) acasing structure having formed therein a fuel passageway into which isto be directed fuel under pressure, substantially flat first and secondfixed internal surface portions substantially parallel with each other,and first and second chambers arranged in series with each otherperpendicularly to said fixed internal surface portions, (b) first andsecond biasing means provided in said first and second chambers,respectively, (c) a first movable member movable in part within saidfirst chambers and in part within said second chambers, (d) a secondmovable member movable within said second chambers and located in thevicinity of the end of the second chambers opposite to the firstchamber, said second movable member having an end face substantiallyparallel with said first and second fixed internal surface portions andlocated at said end of said second chambers, and second biasing meansconstantly engaging said second movable member for urging the secondmovable member into contact with said first fixed internal surfaceportion, (e) a valve element located in the vicinity of said secondmovable member and movable toward and away from the second movablemember for controlling the flow rate of fuel through said fuelpassageway, said valve element having an end face substantially parallelwith and located adjacent said second fixed internal surface portion,(f) said first movable member being constantly engaged by said firstbiasing means and said valve element in the presence of fuel pressure insaid fuel passageway for transmitting from the first biasing means tothe valve element a force urging the valve element toward apredetermined initial position with respect to the second movable memberheld in contact with said first fixed internal surface portion, and (g)intermediate means intervening between said first movable member andsaid valve element, the intermediate means being movable with said valveelement and having an end face substantially parallel with and locatedadjacent to the end face of said second movable member, (h) the distancebetween the end face of said second movable member and the end face ofthe intermediate means engaging the valve element held in said initialposition defining the amount of said preliminary valve lift, and thedistance between said second fixed internal surface portion and the endface of the valve element held in said initial position defining theamount of said full valve lift.
 18. A two-stage opening fuel injectionvalve assembly having a full valve lift and a preliminary valve liftwhich forms part of the full valve lift, comprising(a) a casingstructure having formed therein a fuel passageway into which is to bedirected fuel under pressure, a substantially flat fixed internalsurface portion, and first and second chambers arranged in series witheach other perpendicularly to said fixed internal surface portion, (b)first and second biasing means provided in said first and secondchambers, respectively, (c) a first movable member movable in partwithin said first chambers and in part within said second chambers, (d)a second movable member movable within said second chambers and locatedin the vicinity of the end of the second chambers opposite to the firstchamber, said second movable member having an end face substantiallyparallel with said fixed internal surface portion and located at saidend of said second chambers, said second biasing means constantlyengaging said second movable member for urging the second movable memberinto contact with said fixed internal surface portion, (e) a valveelement located in the vicinity of said second movable member andmovable toward and away from the second movable member for controllingthe flow rate of fuel through said fuel passageway, (f) said firstmovable member being constantly engaged by said first biasing means andsaid valve element in the presence of fuel pressure in said fuelpassageway for transmitting from the first biasing means to the valveelement a force urging the valve element toward a predetermined initialposition with respect to the second movable member held in contact withsaid fixed internal surface portion, and (g) intermediate meansintervening between said first movable member and said valve element,the intermediate means being movable with said valve element and havinga first end face defining a plane substantially parallel with andlocated adjacent to a plane defined by said fixed internal surfaceportion and a second end face defining a plane substantially parallelwith the plane defined by said first end face and spaced apart more fromthe plane defined by said fixed internal surface portion than a planedefined by said first end face, (h) the distance between the planedefined by said fixed internal surface portion and the plane defined bythe first end face of the intermediate means member engaging the valveelement held in said initial position defining the amount of saidpreliminary valve lift, and the distance between the plane defined bysaid fixed internal surface portion and the plane defined by the secondend face of the intermediate means engaging the valve element held insaid initial position defining the amount of said full valve lift.
 19. Atwo-stage opening fuel injection valve assembly having a full valve liftand a preliminary valve lift which forms part of the full valve lift,comprising(a) a casing structure having formed therein a fuel passagewayinto which is to be directed fuel under pressure, a substantially flatfixed internal surface portion, and first and second chambers arrangedin series with each other perpendicularly to said fixed internal surfaceportion, (b) first and second biasing means provided in said first andsecond chambers, respectively, (c) a first movable member movable inpart within said first chambers and in part within said second chambers,(d) a second movable member movable within said second chambers andlocated in the vicinity of the end of the second chambers opposite tothe first chamber, said second movable member having an end facesubstantially parallel with and confronting said fixed internal surfaceportion, said second biasing means constantly engaging said secondmovable member for urging the second movable member into contact withsaid fixed internal surface portion, (e) a valve element located in thevicinity of said second movable member and movable toward and away fromthe second movable member for controlling the flow rate of fuel throughsaid fuel passageway, (f) said first movable member being constantlyengaged by said first biasing means and said valve element in thepresence of fuel pressure in said fuel passageway for transmitting fromthe first biasing means to the valve element a force urging the valveelement toward a predetermined initial position with respect to thesecond movable member held in contact with said fixed internal surfaceportion, and (g) intermediate means intervening between said firstmovable member and said valve element, the intermediate means beingmovable with said valve element and having an end face substantiallyparallel with and located adjacent to the end face of said secondmovable member, (h) said valve element being movable from said initialposition to a first critical position having the end face of saidintermediate means held in contact with the end face of said secondmovable member for defining the amount of said preliminary valve lift bythe distance between the end face of said second movable member and theend face of the intermediate means engaging the valve element held insaid initial position.
 20. A two-stage opening fuel injection valveassembly as set forth in claim 19, in which said fixed internal surfaceportion is one of first and second fixed internal surface portionsformed in said casing structure and substantially parallel with eachother and is constantly contacted by said second movable member and inwhich said valve element has an end face substantially parallel with andlocated adjacent said second fixed internal surface portion, said valveelement being further movable from said first critical position to asecond critical position having its end face contacted by said secondfixed internal surface portion for defining the amount of said fullvalve lift by the distance between said second fixed internal surfaceportion and the end face of the valve element held in said initialposition.
 21. A two-stage opening fuel injection valve assembly as setforth in claim 19, in which said intermediate means comprises a flangemember formed separately of and securely engaged by said valve elementand having a bore through which said valve element is held in engagementwith said first movable member in the presence of fuel pressure in saidfuel passageway, said flange member having a first end face defining aplane substantially parallel with and located adjacent to a planedefined by said fixed internal surface portion and a second end facedefining a plane substantially parallel with the plane defined by saidfirst end face and spaced apart more from the plane defined by saidfixed internal surface portion than a plane defined by said first endface, said valve element being further movable from said first criticalposition to a second critical position having the second end face ofsaid flange member located at a plane defined by said fixed internalsurface portion for defining the amount of said full valve lift by thedistance between the plane defined by said fixed internal surfaceportion and the second end face of said flange member engaged by thevalve element held in said initial position.